<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div>aa</div>
    <form action="/entry_request">
        <input type="file" id="file"multiple/>
        <input type="submit" value="submit"/>
    </form>
    <script type="text/javascript">
        let file = document.getElementById("file")
        file.onchange = e => {
            console.log(e);
        }
    </script>
</body>
</html>